import java.util.Scanner;

public class h_5 {
    public static void main(String[] args) {
        System.out.print("输入学生成绩：");
        Scanner sc=new Scanner(System.in);
        int cj=sc.nextInt();
        System.out.println("成绩为:"+((cj<60)?"C":((cj<90)?"B":"A")));
    }
}
